lecture14 - Water on Mars Today low pressure prevents...

1 Extraterrestrial Life: Spring 2008 Water on Mars Today, low pressure prevents liquid water from being stable on the surface, but substantial reservoirs of water at the poles as ice and (?) in the subsurface. • was the water ever present as liquid - for how long, and how much? • role in shaping landforms on Mars • is any liquid water present now underground? Evidence • from orbit (morphology of landforms) • from experiments on landers Progress in imaging: Viking orbiters: ~25m per pixel maps Mars Global Surveyor : 1.5 - 12m per pixel Mars Reconnaissance Orbiter : 30cm per pixel Dunes at the South Pole from HiRISE imagery Water vs lava features Alluvial fan in China • running water • standing water • ﬂoods Some craters on Mars seem to have been formed from impacts into water-rich terrain: Yuty crater: ~20km across Has an ejecta blanket that appears to have ﬂowed across the surface - as if icy material was melted so the ejecta was ﬂuid older crater that the ejecta seems to have

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